1. Field of the Invention
The present invention relates to a wheel angular acceleration sensor for a vehicle anti-lock control device, and particularly, to an improvement in a wheel angular acceleration sensor comprising a flywheel rotatably and slidably supported on an output shaft rotated in association with a wheel braked by a wheel brake, a friction clutch plate which normally transmits a driving torque of the output shaft to the flywheel and which allows overrun rotation of the flywheel when the wheel is about to lock at the braking, and a cam mechanism responsive to the overrun rotation of the flywheel to impart axial displacement thereto, said friction clutch plate and said cam mechanism being interposed in series between said output shaft and said flywheel, said axial displacement of the flywheel being outputted as a signal for controlling a braking force of the wheel brake.
2. Description of the Prior Art
Such a wheel angular acceleration sensor has been already known as described, for example, in Japanese Patent Publication Kokai No. 58-126241.
In conventional angular acceleration sensor, a friction clutch plate is disposed parallel with a plane perpendicularly crossing the axis of an output shaft and is not tiltable relative to that plane. This sometimes brings forth inconveniences in that if a machining error is present in a cam mechanism, when the cam mechanism is operated, an unbalanced load may be exerted between driving and driven cam plates to apply a thrust obliquely, i.e., in an inclined direction relative to the axis of the output shaft, from the cam mechanism to a flywheel to impair smooth axial displacement of the flywheel, and than an unbalanced load may be exerted also to a frictional surface of the friction clutch plate to vary the slip characteristic of the friction clutch plate.